The present invention relates to an open-end spinning unit of the type including a fiber guide disc arranged so that at least its largest diameter section extends into the opening of the spinning rotor.
Open-end spinning units with stationary fiber guide discs are disclosed in German Auslegeschrift [Published Patent Application] No. 1,111,549. In the arrangement disclosed therein, the fiber guide disc is arranged with respect to the spinning rotor so that a narrow space remains between the surface of the fiber guide disc and the inner bottom surface of the rotor. The yarn formed in the fiber collecting trough is guided through this space. Consequently, the fiber guide disc serves the purpose of providing sufficient separation between the fibers entering the fiber collecting trough and the yarn removed therefrom.
The drawback of the known arrangement is that the stationary fiber guide disc substantially influences the movement of air in the spinning rotor and leads to turbulences and eddies in the region of the fiber collecting trough. The essential cause of this interference with the spinning process is the substantial difference in speed between the fiber guide disc and the fiber collection trough of the spinning rotor which rotates at high speed.
In order to remove the above-described drawbacks, an open-end spinning unit has been developed which has a break-up roller arranged coaxially with the spinning rotor and in which the break-up roller is provided with a fiber guide edge at its portion facing the spinning rotor. The fiber guide edge together with the associated housing edge forms a substantially radial annular gap through which the break-up roller brings separated fibers to the spinning rotor. Such an arrangement is disclosed in German Offenlegungsschrift (Laid-Open Application No. 2,064,697.
The drawback of this known open-end spinning unit is that the speed of the fiber guide disc is not independent of the speed of the break-up roller since the latter, in view of conditions in its combing range, cannot rotate at any desired high speed. In this case there consequently likewise exists a relatively great difference in speed between the associated housing edge and the spinning rotor.